Lapping machine



May 23, 1939. F. H. MARKWICK .El' AL LAPPING MACHINE Filed July 5, 19352 Sheets-Sheet 1 (Ittorneg May 23 13%.

F. H. MARKWICK ETAL LAPPING MACHINE Filed July 5, 1935 2 Sheets-Sheet 2Patented May 23, 1939 LAPPING MACHINE Frederick H. Markwick and Louis F.Poock, Dayton, Ohio, assignors to The Sheffield Gage Corporation,Dayton, Ohio, a corporation of Ohio Application July 5, 1935, Serial No.29,794

14 Claims.

This invention relates to lapping machines.

One of the principal objects of the invention is the provision of alapping machine of simple construction that is readily adjustable foroperation on work pieces within a wide range of size variation.

Another object of the invention is the provision of such a lappingmachine upon which a single workpiece may be quickly and accuratelylapped.

Another object of the invention is the provision of a lapping machinehaving a flat rotatable lapping disk that is adjustably movable todifferent paths of travel for coordinated movement with a particularworkpiece whereby an improved in lapping action is obtained and the lapface is maintained flat for an extended period of usefulness.

Anotherobject resides in the method of lapping a workpiece of circularcross section that is rotated on its own axis by engagement with arotating lapping surface, and is additionally moved with respect to thelapping surface so that the zone of contact is substantially the entirelapping surface.

A further object of the invention is the provision of a lapping machinehaving a work support of such character that the workpiece, whilesecurely held, is free to move into proper operating relationship withthe lap face.

Other object's and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

In the drawings, which disclose a preferred embodiment of theinvention:-

Fig. 1 is a plan view of the lapping machine constructed in accordancewith the present invention;

Fig. 2 is a transverse vertical sectional view V taken on the line 22 ofFig. 1;

Fig. 3 is an enlarged fragmentary view of a portion of the work support;

Fig. 4 is a sectional view as indicated by the line 4-4 of Fig. 1; a

Fig. 5 is an enlarged fragmentary view of a portion of Fig. 4; and

Fig. 6 is a fragmentary view showing a modified form of lapping disk.

In the drawings, in which like characters of 50 reference designate likeparts throughout the several views thereof the lapping machine isillustrated as comprising a bed I0 having suitable supporting legs H andI2. Toward one end of the bed is mounted a head I3 that supports a 55lapping member, shown as a disk l4, and toward the opposite end of thebed is mounted a work support that is designated generally by thenumeral I6.

The mounting for the lapping disk is shown as comprising a member I8that is fixedly attached to the bed I!) and'has spaced upstanding armsI9 incorporating bearings for free rotation of a spindle 2|. The end ofthe spindle extending toward the center of the machine projects beyondits bearing 20 for attachment of the lapping disk. Driving means areprovided for the lapping disk in the form of a stepped cone pulley 23which is fixedly mounted on the spindle intermediate the arms 19 and isadapted to carry a belt connecting to a suitable source of power.

That portion of the spindle to which the lapping disk is attachedterminates in an enlarged end 25 having a flat end face 26 against whichthe lapping disk is adapted to rest. The face 26 is accurately machinedto afford a flat surface that is perpendicular to the spindle axis. Aslot 21 is provided in the end piece 25 and extends across the end face26 on a diameter thereof. This slot is widened adjacent its bottomportion as indicated at 28 for reception of the head 29 of a threadedmember 30 that attaches the disk M to the spindle. The member 30 isadjustably slidable in the slot and may be fixedly held at any desiredposition therein.

The lapping disk [4, which is preferably made of cast iron or some suchmaterial that is suitable for use as a lap, has a circular peripheraledge 32 and parallel flat end faces; the end face 33 lying in surfacecontact with the face 26 of the part 25 and the opposite face 34 servingas the lapping face with which a workpiece is engaged during the lappingoperation. The disk has a central circular opening 35 therein which,toward the lap face 34, is widened into an annular recess as indicatedat 36. A sleeve 31, which is receivable on the member 30, serves as abearin for the lapping disk. One end of the sleeve has a projectingflange 38 which overlies the disk opening 35 within the recess andserves to hold the disk against the plate 25. A nut 40 which engages themember 30, serves to hold the sleeve in clamped engagement on the endface of the part 25. As shown, the recess 36 is of suflicient depth toaccommodate the projecting parts of the attaching means below the planeof the lap face 34. The proportioning of the sleeve parts. is such thatthe disk l4 may rotate with respect to the spindle upon which it ismounted. The disk H has a running fit on the sleeve. The sleeve lengthunder the flange, although such as tohold the diskin surface engagementwith the end-face 26, affords sumcient freedom that the disk may rotateindependently of the spindle.

The work support I6 is shown as comprising relatively movableinterfitting plates 48 and 4| of which the plate 48 is fixedly mountedto the bed l8 while the plate 4| has adjustably mounted thereon asupporting structure for holding a workpiece in contact with the lapface and for moving the workpiece with respect to the lap face while inoperating engagement. The interconnection of the parts 48 and 4| is inthe form of interlocking ways common to machine tool practice and asindicated at 42. The ways stand so that the path of travel of themovable part is transverse to the spindle axis. Adjustably mounted onthe movable plate 4| is a block 44 that is provided with interfittingways 45 slidably engaging and supporting a carriage 46 for adjustingmovement in the direction of the spindle axis. As shown, attachment orthe block 44 to the'movable plate 4| is by means of screws 48 thatextend through curved slots 49 in the block and threadedly engage theplate 4|. The slots 49 are curved on a radius as defined by an imaginarycenter existing at the midpoint of the screws 48. The slots are ofsufficient length to permit a slight amount of angular movement of theblock 44.

0n the block 44 intermediate the ways 45 is an upwardly extendingprojection 58 which is threaded to receive a screw 5| that is rotatablycarried bythe carriage 46 as indicated at 62. The screw 5| has fixed toit a crank 58 for rotation thereof whereby thecarriage may be moved withrespect to the block in the direction of the spindle axis. The carriage46 has an upwardly extending projection 55 that is provided with 'anopening 56 extending coaxial with the spindle for attachment of a.yoke-shaped member 58 that in turn serves as a support for a workcarrying frame. The proportioning of the sev-. eral' parts that make upthe work support is such that the center of the carriage opening 56 issubstantially the same elevation as the axis of rotation of the lap. Theyoke shaped member 58 has projecting from one end thereof a stud 51which is closely received within the carriage opening 56 and is adaptedto be held therein by a nut 59. The stud 51 extends oppositely to andstands substantially midway between spaced parallel arms 68. The arms818, toward their outer ends, each have a threaded opening 6| forreception of a bearing pin 62. The pins have conical ends 63 and areaxially aligned to engage and pivotally support a work carrying-frame64.

The work carrying frame 64 is arranged as a relativelylong bar likeportion 65 having inclined guide faces 66 at the opposite sides of oneface thereof for accurately mounting a pair .of adjustable work holdingmembers 61. At the midpointof the bar 65 are provided yoke like one endof a workpiece and each holder includesmeans whereby it may be supportedby and adjustably fixed to the part 64. As shown, the bar like portion65 has a slot 16 extending parallel to the inclined faces 66. The slothas an enlarged bottom portion 15 for reception of the head of aclamping member 16 by which the work holders are held tothe frame 64.Each holder 61 has a rockable shaft 11 extending into the lower portionthereof which on the exposed ,end has an accessible crank arm 19 and onthe enclosed end has mounted thereon a cam 88 that is engaged by theloop end 8| of the clamp: ing member 16. The proportioning of the cam,holding member and parts associated therewith is such that in oneposition of the cam the holding members may be slidably moved along thebar like portion and in another position the holding members aresecurely locked in place on the bar like portion 65.

The work holders 61, by which the pivot centers I are carried, areadjustably mounted so that the spacing of the centers may be altered toaccommodate a wide variety of sizes of workpieces. In addition, and forconvenience in handling the workpieces, one of the pivot centers isadjustable in its holder 61 so that it may be readily withdrawn, whendesired in order to afford a greater spacing for'attachment or removalof a workpiece from the centers. As shown, the right hand center 12 isslidably mounted within a socket 82 of the holding member 61 and has astud projection 83 that extends through the end of'the socket and hasattached thereto a finger piece 85 by which the center 12 maybe movedaxially against the tension of a spring 84 that is positioned within thesocket and bears against the pivot center urging it outwardly toward theopposite center 12. adjustable holder is such that its center may beheld in the withdrawn position when desired. The holder end on thesocket axis has a cross slot- 86 of such width to receive the thindisk-like finger piece 85. By withdrawing the center and turning thefinger piece to a position removed from'the slot the center is held inretracted position. Locking means are provided The arrangement of thefor the right hand center in the form of a screw an upstanding arm 94which is pivotally mounted at 95 on the machine leg 2. The upper end ofthe arm 94 has pivotally connected to it at 96 a link 91 which ispivotally connected at '98 to the movable plate 4|. Oscillation of thehandle 9| produces a reciprocatory movement of the work support.

workpieces of the character that are subjected -to a lapping operationhave some provision for mounting them between centers. That is, theyeither have accurately aligned conical centers for mounting on thesupporting centers 12, -or they have a central opening therethroughwhereby they may be mounted .on a'suitable arbor which in turn may bemounted on the centers 12. In any event the workpieces are so arrangedthat they may be carried between the centers 12 in such a manner thatthe surface that is to I be lapped is concentric to the axis of"rotation of the workpiece. In Fig. 1 the workpiece that is illustratedin dotted outline comprises acylindrical plug I88 which is shown carriedby an arbor |8|that is mounted on the centers 12.

As has been pointed out above, the machine is readily adjustable toaccommodate workpieces within a wide range of size variation.- Thesepieces may be shorter or longer than the one illustrated'and the greatmajority of them will be considerably shorter than the radial length ofthe lap face so that in any one position of contact with the lap faceonly a part of the radial length of the face will be engaged. Theabrading action of the lapping operation removes metal from the lap faceas well as from the workpiece.- A lap, to provide a desired lappingoperation, must remain flat. There is provision in the machine wherebythe workpiece is caused to traverse a path with respect to the lap facesuch that substantially the entire face of the lap contacts with theworkpiece so that any wear on the lapping face as a result of thelapping operation is uniform and as a result the face remains flat. Thisdesirable feature of uniform wear is obtained by provision of areciprocatory work support which may be reciprocated during the lappingoperation, and by provision of an adjustable eccentric mounting for thelapping disk such that it traverses an eccentric path during rotation.In addition to this there is means provided for moving the lapping diskwith respect to its supporting spindle so that the'driving relationshipof these parts isintermittently changed during use.

As mentioned above, the stud 30 that serves as an attaching meansbetween the lapping disk and its support is carried within a transversegroove 21. The provision of this slotted engagement enables the operatorto provide any desired degree of eccentric travel in the lapping disk.As is shown'in Fig. 2, the center of rotation of the disk is indicatedat I02 and is eccentrically related to the center of rotation of thespindle as indiated by the numeral I03. This association of partsresults in a planetary motion being imparted to the disk. Rotationof thedisk on the spindle or the change in related positioning of the diskwith respect to the spindle occurs as a result of frictional dragproduced by contact of the workpiece or by provision of means such as afriction brake I04 which is shown carried by an arm I05 extending fromthe bed I0 to position the brake so that it may contact with theperipheral edge 32 of the lapping disk. The brake comprisesa threadedshaft portion I06 that threadedly engages the bracket and which has onone end thereof a cross pin I01 by which it may be convenientlyadjusted.

The opposite end of the member I06 is socketed at I00 for reception of ablock of some resilient substance such as leather which willfrictionally engage the periphery of the lapping disk during itsrotation and will momentarily stop the .disk or will at least impartsome rotational movement of the disk with respect to its spindle. Thebrake is adjustable so that the desired contacting engagement may bemaintained for different degrees of eccentric positioning of the lappingdisk and so that, when desired, the brake may be withdrawn entirely fromcontacting en-' gagement. Referring further to the rotatable mounting ofthe lapping disk, as has been pointed out, the fit of the pivot sleeve31 within the disk center is such as to hold the disk in surface contactwith the end face of the spindle and, although sufliciently loose topermit relative movement, it is likewise sufficiently tight to avoidobjectionable shake or vibration. The disk is quite heavy and, althoughrotatably mounted,

there is sufficient friction between the disk and its support to causeit to revolve upon rotation of the spindle. Also, because of thisdriving relationship, but little resistance is required to causerelative movement between the disk and its spindle. This desirablerelative movement that provides for full coverage of the disk surfaceand resulting uniform wear may occur only as a result of contactingengagement of the workpiece with the disk and without use of thefriction brake. During the lapping operation the workpiece bears butlightly against the lapping disk and is readily adjusted to a desiredengaging relationship by adjustment of the carriage screw 5|. Even.though the frictional engagement is but a light contact there issuflicient friction between the engaging parts which is effective,particularly when the workpiece engages the disk adjacent the peripherythereof, to produce some relative movement of the disk. This may be avery small amount but, as the workpiece is continually sweeping back andforth across the lapping face, the continued repetition of this smallchange of movement is sufiicient to provide the desired action in thedisk.

In the case of very small workpieces or workpieces having but a limitedengagement with the lap face there may not be sufficient frictional dragto move the disk, in which event the friction brake may be resorted toas a means of altering the disk positioning. Here also the brake may beadjusted so that but a very small relative movement is imparted for eachrevolution of the disk. However as this occurs for each turn of the diskthe wear on the disk is made uniform.

Although the work support is of such construction as to provide asubstantial and. rigid support'of the workpiece such that objectionableshake or vibration is avoided, it is likewise so constructed to providea movable support for the workpiece so that the workpiece may freelyassume a proper operating relationship with the lap face. The workcarrying frame 64 is free to swing on its pivot centers 63 so thatregardless of whether the workpiece has a cylindrical or taperingperipheral face it may readily move to a positioning such that theworkpiece properly engages the lap face. Friction means are providedbetween the frame 64 and its supporting structure to prevent too muchfreedom of movement at this point. As shown, the yoke arms 60 havetransverse passages therethrough for reception of contact balls IIO thatare urged into contacting engagement with the arms 68 through pressureexerted by a spring III that is compressed between the ball I I0 and athreaded plug H2. The tension afforded by the springs III is onlysufficient to overcome an objectionable freedom of movement of the frame64. Free rotation of the workpiece on its centers is assured byprovision of the locking screw 88 which permits the centers to bepositioned at a desired spacing to thus avoid an objectionabletensioning to these parts which might result from the tensioning of thespring 84.

Unusually long workpieces are readily accommodated in this machine byarranging the machine to permit the application of a lap of increaseddiameter. As such operation may be required but seldom the largediameter lap is member, H5 having oppositeparallel faces of which theface I I6 lies in surface contact with the lap face 34 and the oppositeface H1 is then utilized as the lapping face. This disk is mountedthrough provision of a central circular passage ll8 that receives ascrew H9 which threadedly engages the stud 30. An enlarged recess I20 inthe lap face accommodates the head I2l of he holding screw.

Through provision of this machine an operator is enabled to quickly andaccurately provide a superior lapped surface on a workpiece such, forexample, as a gage plug. The machine is flexible in that it is providedwith a sufficient range of adjustment to readily accommodate plugswithin a wide range of size variation and further, it is so arrangedthat either cylindrical or tapered plugs may be handled. It is furtherpointed out that as no special adjustments are required other than anadjustment of the'holding, I device a single workpiece of .a given sizemay be handled within a unit of time practically no longer than the unittime for a plurality of pieces of the same size. As the carriage travelis under control of the operator so that the work piece may be caused tosweep the full width of the lap face it may not be necessary to changethe degree of eccentricity of the lap face except to handle widelydiffering work pieces. A single lap may be utilized for any plugthat maybe accommodated and, as mentioned above,'in the case of unusually longplugs an auxiliary lapping disk may be readily attached. Because of'theirregular and constantly changed motion of the disk with respect to theworkpiece uniform wear on the lapping face is afforded and, in addition,a superior and highly polished surface is provided on the workpiece.

While the method herein described, and the form of apparatus forcarrying this method into eifect, constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without'departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A lapping machine comprising a rotatable lapping member having a flatlapping face, drive means effective on the lapping member to impartv ofthe work piece with respect to the axis of rotation of the lappingmember, means for holding a workpiece in engagement with said lappingmember, and means for moving the work piece across the face of thelapping member to inde- .terminately vary the driving relationship be-'tween the drive means and the lapping member. 2. A lapping machinecomprising a lapping member comprising a circular disk having a flatlapping face and having a mounting portion at the center thereof, meansfor rotatably holding a workpiece having a curved surface of revolutionin engagement with the lapping flat face of the member, means for movingthe holding means across the face of the lapping member, supportingmeansfor the lapping member comprising a rotatable spindle, means' onthe spindle slidable transversely of the spindle axis and rotatablysupportingthe mounting portion of the lapping gagement with the lappingmember, supporting means for the lapping member comprising a rotatablespindle, said spindle havingan end portion extending transversely of thespindle axis and terminating in a flat face extending perpendicular tothe spindle axis, and mounting means rotatably carrying thelappingmember by engagement with the central opening thereof and havingan interfltting connection with the spindle for support of the lappingmember on the spindle with one face of the lapping member and the endface of the spindle in surface contact, said mounting means beingadjustable on the spindle end portion for adjustably varying theeccentric relationship of the lapping member center with respect to thespindle axis of rotation.

4. A lapping machine comprising a circular disk-like lapping memberhaving flat parallel faces of which one face is the lapping face, saidlapping member having a central opening therethrough terminating in anenlarged recess at the lapping face, means for holding a workpiece inengagement with the lapping member, a rotatable spindle for the lappingmember, a sleeve extend- Y plane of the lapping face.

5. A lapping machine comprising a lapping member having a flat lappingface,'means for holding a workpiece in engagement with the lappingmember, supporting means for the lapping member comprising a rotatablespindle, means rotatabiy mounting the lapping .member on the spindlewith the lapping member flat face extending perpendicularly to thespindle axis, and

friction means intermittently operable during a lapping operation tomove the lapping member with respect to the spindle.

. 6. A lapping machine comprising a lapping member having a lappingface, means for holding a workpiece in engagement with the lappingmember, supporting means for the lapping member comprising a rotatablespindle, means rotatably mounting the lapping member on the spindle withthe lapping face extending perpendicularly to the spindle, and meansintermittently engaging the lapping member upon rotation of the spindleto impart relative movement to the lapping member with respect to thespindle. 7. A lapping machine comprising a base, a lapping membercomprising a circular disk-like member having a flat lappingface, meanson the base for holding a workpiece in engagement with the lappingmember, supporting means on the base for the lapping member comprising aretatable spindle, means rotatably mounting the lapping member on thespindle with the lapping member flat face extending perpendicularly tothe spindle, and means adjustably supported from the lapping machine tointermittently contact the lapping member in frictional engagement uponrotation of the spindle for momentarily holding the lapping member.

8. A lapping machine comprising a rotatable spindle; a lapping membereccentrically mounted thereon and having driving engagement therewithonly by virtue of frictional contact, said lapping member having alapping face extending perpendicularly to the spindle axis, supportingmeans for holding a workpiece in engagement with the lapping member,said supporting means comprising a frame having axially relatedpoints ofsupport defining an axis of rotation for the workpiece, means rockablysupporting said frame for free turning movement on an axis extendingtransversely through the axis of rotation of the workpiece and extendingtransversely of the spindle axis, and means for reciprocating the framein the direction of the plane of the lapping member face for traverse ofa supported workpiece across the lapping face towards and away from theaxis of rotation of the spindle.

9. A lapping machine comprising a rotatable spindle having a lappingmember providing a lapping face extending perpendicularly to the spindleaxis, supporting means for holding a workpiece in engagement with thelapping member comprising a rockable frame having a barlike portion,spaced members adjustably mcvable on the bar-like portion, said membershaving axially aligned pivot members defining an axis of rotation for aworkpiece, said bar-like portion having members extending oppositelyfrom each side adjacent the midpoint thereof and curving toward oneanother to form a U-shaped yoke of which the member ends continue beyondthe axis defined by the axially related pivot members, a movablecarriage for the frame comprising yoke-like arms encircling the membersof the bar-like portion, and axially related bearing means connectingthe yoke-like arms of the frame and carriage on a line extending throughthe axis of rotation of the pivot members and extending transversely tosaid axis of rotation and to the axis of rotation of the spindle.

10. A lapping machine comprising a lapping member having a lapping face,a rotatable spindle supporting said member and frictionally engagedtherewith to provide rotation of the lapping member on the spindleduring operation, means for rotating said spindle, a work holder havingcentering means for rotatably supporting a workpiece for movement aboutan axis extending angularly to the axis of rotation of the spindle, asupport carrying said work holder for movement about an axis extendingsubstantially transverse of the work axis, and means for moving the worksupport so that all of the work which engages the lapping face movestoward the axis of rotation of the spindle or moves away from the axisof rotation of the spindle to indeterminately vary the drivingrelationship between the spindle and the lapping member.

11. A lapping machine comprising a lapping member supported for freeturning movement with respect to a fixed axis, said lapping memberhaving a lapping face, rotatable means frictionally engaging saidlapping member and adapted to impart a rotative driving force thereto byvirtue of frictional contact therewith which is small enough to producea substantial frictional slip of the lapping member with respect to therotatable means dunng operation, and means for holding a curved surfaceof revolution in rolling contact with the face of the lapping member forrotation thereby and for moving the surface of revolution thereacross asa means of influencing the driving effort acting between the rotatablemeans and'the lapping member to influence the rotation of the lappingmember and vary the rotational relationship between the surface ofrevolution and the lapping member.

12. A machine of the character described comprising a member having awork engaging lapping face, a rotatable spindle supporting said lappingmember eccentrically of the axis of retation of the spindle andfrictionally engaged with the lapping member to provide relativerotation during operation, means for rotating the spindle, a worksupport having centering means for rctatably supporting the work formovement about an axis extending angularly to the axis of rotation ofthe spindle, and means for moving the work support to move the workacross the face of the lapping member and indeterminately vary thedriving relationship between the spindle and the lapping member.

13. A lapping machine comprising a lapping member having a flat lappingface, means for rotatably holding a workpiece having a curved surface ofrevolution in engagement with the flat face of the lapping member,supporting means for the lapping member comprising a rotatable spindlethe axis of which is angularly related to the axis of rotation of theworkpiece, means eccentrically and rotatably mounting the lapping memberon the spindle with the lapping m'em bers flat face extendingperpendicularly to the spindle axis and providing driving relationshipbetween the spindle and the lapping member effective only throughfrictional contact for variation of the driving relationship between thespindle and the lapping member during operation, and means for movingthe workpiece across the face of the lapping member.

14. A lapping machine comprising a lapping. member having a lappingface, means for rotat-' ably holding a workpiece having a. curvedsurface of revolution in engagement with the lap-' ping face, supportingmeans for the lapping member comprising a rotatable spindle the axis ofrotation of whiclris angularly related to the axis of rotation of theworkpiece, means adjustably attachable to the spindle at varying amountsof eccentricity with respect to the spindle axis and rotatably mountingthe lapping member with the lapping face extending transversely of thespindle axis and providing driving relationship between the spindle andthe lapping member effective only through frictional contact such thatrelative rotational movement of the spindle and lapping member occursduring operation, and means for moving the workpiece across the face ofthe lapping member.

' FREDERICK H. MARKWICK.

LOUIS F. POOCK.

